Abstract

Self-assembled magnetic semiconductorquantum dots have been grown on Si (001) substrates using dropletepitaxy by molecular-beam epitaxy. Structural characterization reveals that these dots possess a zinc-blende lattice. The quantum dots with 8% Mn content are ferromagnetically soft and slightly anisotropic at low temperature, and show the superparamagnetic behavior with a blocking temperature of 20 K in the in-plane direction. Moreover, the results of x-ray absorption near edge structure provide direct evidences for the substitutional ion with a half-filled configuration for the Ga site, suggesting the hole-mediated ferromagnetism in zero-dimensional quantum dots.